Al-Qaida is on the verge of producing radioactive weapons after sourcing nuclear material and recruiting rogue scientists to build "dirty" bombs, according to leaked diplomatic documents.

A leading atomic regulator has privately warned that the world stands on the brink of a "nuclear 9/11".

Security briefings suggest that jihadi groups are also close to producing "workable and efficient" biological and chemical weapons that could kill thousands if unleashed in attacks on the West.

Thousands of classified American cables obtained by the WikiLeaks website and passed to The Daily Telegraph detail the international struggle to stop the spread of weapons-grade nuclear, chemical and biological material around the globe.

At a Nato meeting in January 2009, security chiefs briefed member states that al-Qaida was plotting a program of "dirty radioactive IEDs", makeshift nuclear roadside bombs that could be used against British troops in Afghanistan.

As well as causing a large explosion, a "dirty bomb" attack would contaminate the area for many years.

The briefings also state that al-Qaida documents found in Afghanistan in 2007 revealed that "greater advances" had been made in bioterrorism than was previously realized. An Indian national security adviser told American security personnel in June 2008 that terrorists had made a "manifest attempt to get fissile material" and "have the technical competence to manufacture an explosive device beyond a mere dirty bomb".